The National Music Publishers Association (NMPA) announced Wednesday that artist and musician Yoko Ono would be added as a co-writer on “Imagine,” one of her late husband John Lennon’s most popular solo songs.

Yoko Ono attends the opening of her exhibition "Land of Hope" at the Museum of Tolerance and Memory in Mexico City, Mexico, in February 2016. The National Music Publishers Association has announced that Yoko Ono is to receive a co-writing credit on the 1971 song "Imagine."SASHENKA GUTIERREZ / EPA

Ono and her son Sean Ono Lennon were on hand at the organization’s annual meeting to receive its Centennial Song award for “Imagine,” which debuted in 1971. NMPA president David Israelite made the announcement after playing a clip from a BBC interview Lennon did just days before he was killed in 1980. In the video, he explained how the much-beloved ballad came to be.

“It was right out of 'Grapefruit,' her book. There’s a whole pile of pieces about 'Imagine this' and 'Imagine that.'”

“Actually that should be credited as a Lennon-Ono song because a lot of it — the lyric and the concept — came from Yoko. But those days I was a bit more selfish, a bit more macho, and I sort of omitted to mention her contribution. But it was right out of 'Grapefruit,' her book. There’s a whole pile of pieces about 'Imagine this' and 'Imagine that,'” Lennon said in the video, referencing Ono's self-published 1964 book "Grapefruit."

In that same interview, Lennon goes on to admit that sexism was a big part of the reason that he was reluctant to credit Ono for her artistic contributions to the song.

“If it had been Bowie, I would have put 'Lennon-Bowie,' you see. If it had been a male, you know. ... Harry Nilsson — 'Old Dirt Road,' it's 'Lennon-Nilsson,'" he said. “But when we did [“Imagine”]. I just put 'Lennon' because, you know, she's just the wife and you don't put her name on, right?'"

Upon hearing the news she’d be getting a writing credit for the song, Ono emotionally told the crowd that “this is the best time of my life,” according to Variety. In a Facebook post published after the ceremony, Sean Ono Lennon said it was the “proudest day of my life,” adding that his mother “[welled] up in tears,” upon hearing the news.

The National Music Publishers Association did note it may take some time before the co-writing credit becomes official. Israelite told Variety that while the process was already underway, there might be some opposition because a copyright for a song extends for 70 years after the writer’s death.

As for Ono, she has continued her artistic and musical career in the years since Lennon’s death, and last released an album, titled “Take Me to the Land of Hell,” in 2013.

She and her label also re-released three of the albums she did with Lennon, “Unfinished Music No. 1: Two Virgins,” “Unfinished Music No. 2: Life with the Lions,” and “Yoko Ono/Plastic Ono Band” last year.